DESCRIPTION (Adapted from applicant's description): The investigators plan to produce canine clones for genes that are known to be expressed in testis development and define the temporal and spatial expression patterns of these genes in normal canine embryonic gonads. The specific aims are: 1) To clone the entire coding sequence of canine SOX-9. The investigators are currently screening a canine genomic DNA library with a human SOX-9 that hybridizes to canine DNA. Homologous regions will be subcloned and characterized by sequence analysis. 2) To clone canine genomic DNA sequences of MIS (Amh), Wt-l, and SF-1. They will use standard library screening methods and polymerase chain reaction (PCR) to identify clones in a genomic DNA library. Regions of homology will be subcloned and their identity confirmed by sequence analysis. 3) To characterize the temporal and spatial expression patterns of Sry, Sox 9, MIS, Wt-1 and SF-1 in normal canine embryonic gonads, using reverse transcriptase PCR and in situ hybridization with canine probes. At the end of this study, they will be poised to examine the temporal and spatial expression patterns of these genes in affected embryos, which will be critical to understanding the genetic mechanisms responsible for abnormal testis development.